Project, how to debug

[Andrew Farrell]

points of general advice:
- As noted by Chris, you first need to figure out what the code is
*supposed* to do.
- Have a notebook and pencil next to you as you are working through this so
that you can make notes and draw out the structure of things.
- Write down the general structure of the code on your notebook so you
always keep yourself oriented. If you find yourself lost, don't just keep
reading code; stop and write out what you do understand and try to turn
your sense of confusion into concrete questions.
- Use The Silver Searcher <http://geoff.greer.fm/ag/>. If you find yourself
thinking "I wish I could just see all the places where the variable
'herring' is used", then `ag -C 5 herring` is going to be your friend.
- Use pdb <https://docs.python.org/2/library/pdb.html>, the python debugger
that comes in the standard library. If you find yourself wanting to jump
into a section of the code and print out variables and look at stack
frames, sticking `import pdb;pdb.set_trace()` in there is going to be your
friend.
- Actually try using ipdb
<https://docs.google.com/presentation/d/1c6BaV6T57z8UjkEd32xQErMtLT0fC-mZOCRaCcP7dcs/edit#slide=id.p>,
which has a slightly better user interface than pdb. But don't worry if you
can't install it. pdb is fine.
- Much like you shouldn't just blindly read through code, don't just
blindly step through code. If you lose sight of where you are, step back
and re-orient yourself.
- Find a colleague, friend, or rubber duck. Explain to them what you think
the code is doing. This will force you to think about things more clearly.
- Try writing unit tests for the code with with py.test
<http://pytest.org/latest/>. It will help you verify "okay, this piece
right here is working correctly" and thereby mean that you don't have to
check that piece again.
- Use assert statements to check that things are as they should be.
- Try sticking `assert False` into the middle of a function. If the
function raises an error other than AssertionError, then the problem is
before the assert statement.
- In your spare time, read 9 Indespensible Rules for Debugging Software and
Hardware Problems
<http://www.amazon.com/Debugging-Indispensable-Software-Hardware-Problems/dp/0814474578>.
It is both useful and enjoyable.

On Tue, Mar 31, 2015 at 7:05 AM, Robert Clove <cloverobert at gmail.com> wrote:

>
>
> On Tue, Mar 31, 2015 at 5:19 PM, Peter Otten <__peter__ at web.de> wrote:
>
>> Robert Clove wrote:
>>
>> > Hi All,
>> >
>> > I am facing a problem.
>> > I have been given a project written in python and asked to debug it.
>> > I have not been given the flow they said understand and debug.
>> >
>> > Can someone suggest me how to debug it in Wings IDE.
>>
>> Are those specific bugs that you are supposed to fix or are you to both
>> find
>> and fix bugs?
>>
>> > Project have approx 10 files.
>>
>> Generally speaking speaking this is not so much a matter of tools; if
>> there
>> is any documentation you can trust reading that is usually the best start;
>> reading the code is important, too.
>>
>> Then you can consider your next steps depending on the "messiness" of the
>> code base and the degree of coverage with unit tests.
>>
>>
>> --
>> https://mail.python.org/mailman/listinfo/python-list
>>
>
>
> There is no documentation provided i have to read the code understand the
> flow first.
>
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>
>
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